In the prior art, boats are known with a wide variety of hull configurations. While the exact shape of the hull often differs from one boat to the next, most boat hulls may be characterized as having a V-shape (in lateral cross-section). In addition, most hulls are adorned with raised or recessed ridges that extend longitudinally along the hull. These ridges are referred to in the art as "chines." Some boat hulls may also incorporate laterally extending ridges or recesses, which are also referred to as chines.
Regardless of their placement and orientation, chines are included on a boat's hull to improve its performance and stability during operation. For example, chines are useful to control lateral motion of the vessel when underway.
Lateral motion, however, is not the only type of motion experienced by boats, especially speed boats. Speed boats operate across a wide range of different speeds. Accordingly, it is possible that a hull that operates acceptably at low speed may not operate acceptably at higher speeds.
One type of motion that may become pronounced at higher speeds is a phenomenon known as "porpoising," which means that the boat tends to rhythmically move up and down while travelling forward. ("Porpoising" refers to the motion of the boat that is like the movement of a porpoise jumping out of the water.)
Porpoising occurs when the center of gravity and the center of buoyancy of the boat are close together but are not in equilibrium with one another.
In most cases, porpoising is more likely to occur when the boat is at a higher speed than when the boat is at a lower speed. At lower speeds, a majority of the hull of the boat is in contact with the water, so the boat is in a condition where the equilibrium between the center of buoyancy and the center of gravity of the boat is not in question. However, as the boat's speed increases, the hull generates greater lift (which is a function of the boat's speed). This means that, at higher speeds, less of the boat's hull contacts the water as the bow of the boat rises out of the water. As a result, equilibrium between the center of gravity and center of buoyancy may not be established, resulting in porpoising of the boat when underway.